#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
void main()
{
	float a = 1;
	float b = 1;
	float num=0;
	float temp;
	int t;
	for (t = 1; t < 21; t=t+1)
	{
		temp = a + b;
		b = a;
		a = temp;
		num = num+a / b;

    }
	printf("%0.2f", num);
}